Lock washer having axially extending tabs of severable, compressible material



July 4, 1961 J..MAY ETAL 2,990,866

LOCK WASHER HAVING X ALLY EXTEN DING TABS OF SEVERABLE, CO ESSIBLE MATERIAL Filed Aug. 9, 1957 3 Sheets-Sheet 1 15in!!! Z,

INVENTORS Tamas a M901 1912 1720 .5. 17121125 Ml-KW ATTORNEY July 4, 1961 J. 0. MA ET AL 2,990,866 LOCK WASHER HAVING AXI LLY EXTENDING T 0F SEVERABLE, COMPRESSIBLE MATERIA Filed Aug. 9, 1957 eats-Sheet 2 IN VENTORS' Mas LMae r fimaznl. 11112? BY 5W ATTORNEY CY ET AL 2,990,866

LLY EXTENDING TABS SSIBLE MATERIAL 5 Sheets-Sheet 3 y 1961 J. c. MA

LOCK WASHER HAVING AXIA OF SEVERABLE, COMPRE Flled Aug 9 1957 INVENTORS g .191; (I Mk0? ALFREJL. 252K122? ATTORNEY United States Patent 2,9%,866 LOCK WASHER HAVING AXIALLY EXTEND- NG TABS OF SEVERABLE, COMPRESSIBLE MATERIAL James C. Macy, 25 S. Wickom Drive, and Alfred L. Smith, 416 Westfield Ave, both of West'field, NJ. Filed Aug. 9, 1957, Ser. No. 676,470 8 Claims. (CL 151--14.5)

The present invention relates to new and useful improvements in fastening devices of the type including an externally threaded fastener member such as a bolt, screw, or the like adapted for threaded engagement with a complementally internally threaded member and an interposed lock washer, and more particularly to improvements in the lock washer for use with such a fastening device and to a method of assembling. the lock washer with the externally threaded fastener member.

In general, this invention contemplates the provision of 'a fastening device of the general type shown in the patent to Waller, Reissue 23,816, in which successive increments of washer prongs or tongues are severed as the cooperating threaded members are tightened relative to one another. In the aforesaid patent, the lock washer prongs or tongues are of metal and initially formed to extend substantially axially of the externally threaded member with the bent tongues being pre-set and slightly spaced outwardly from the threads on said member.

One of the principal objects of the present invention is to improve the locking torquev characteristics of this type of fastening device with an improved lock washer of relatively soft bendable material preferably having some inherent resiliency and compressibility.

Another object of the present invention is, to provide a lock washer having characteristics such that continued back-off torque is required even after the threaded members are relatively loosened to a point where a metal washer would be no longer eifective.

A further object of the invention is to provide a lock washer of the, abovetype having prongs. or tongues initially traversing a central opening in the washer body, and wherein the prongs. or tongues, are deformed by assembly of the washer with the externally threaded member to a position where the prongs or tonguesretain sufiicient inherent resiliency so that they will tend to constantly engage the threads, on the externally threaded member.

A still further object of the invention is to provide a lock. washer of the above type wherein the prongs or tongues will continueto be urged inwardly into engage: ment with the externally threaded member even after successive increments of the. tongues have been severed.

A still further object of the present invention is to pro; vide a lock washer having an increased amount of material available from theprongs or tongues to be, severed and wedged under compression between the threads, of the complemental fastener members, i

The invention still further aims to provide a lock washer which will lend itself to relatively simple and inexpensive manufacturing procedures and which may be formed in the flat and thereafter deformed to operative position as a result of assembly of the. washer with an externally threaded member.

The above and other objects of the invention will, in part, be obvious and will be hereinafter more, fully pointed out.

In the accompanying drawings:

FIG. 1 is a perspective view of an extruded length of washer stock material from which individual washers of different thicknesses may. becut, as, illustrated; by the. dotted lines;

' FIG. 2 is a plan view showing another form of washer 2,990,866 Patented July l, 1961 produced by die cutting a plurality of rows of such washers. from a strip of washer stock material;

FIG. 3 is a top plan view of a washer cut from the stock of FIG. 1;

FIG. 4 is a side viewof the washer of FIG. 3;

FIG. 5 is a fragmentary side elevation showing initial assembly of the washer with the externally threaded member;

FIG. 6 is a view similar to FIG. 5 showing the washer in completely assembled position on the externally threaded member;

FIG. 7 is a side elevation, partly in section, showing initial assembly of a nut with a bolt having the washer assembled thereon;

FIG. 8 is an enlarged view, partly in section, showing the relative positioning of a nut and bolt of FIG. 7, after the same have been tightened relative to one another;

FIG. 9 is an enlarged fragmentary sectional view showing initial positioning of the washer prongs with the nut and bolt substantially at the moment of engagement of the nut therewith;

FIG. 10 is'a fragmentary sectional view, similar to FIG. 9 but showing the nut further advanced, on the boltwith increments'of the washer tongues severed;

FIG. 11 is a view, similar to FIG. 10, but showing still further advance of the nut on the bolt with additional increments of the washer tongues severed;

FIG. 12 is a view, similar to FIG. 11, but showing the nut in its completely tightened position against the annu lar washer body;

FIGS. 13, 14, 15, 16, and 17 are top plan views showing various modifications of the washer tongue formations;

FIG. 18 is a sectional view showing a washer made according to the instant invention as. applied to a machine screw;

FIG. 19 shows a washer made according to the present invention and applied to a screw element with a metal backing washer;

FIG. 20 is a plan view showing the washer of FIG. 14 with an attached plain washer;

FIG. 21 is a side elevation showing the washer assemblyof FIG. 20 applied to a bolt;

FIG. 22 is a side View in section showing a modified form of two-part washer;

FIG. 23 is a plan view of a further modified form ofwasher with a single enlarged tongue or prong;

FIG. 24 is a side View in section showing the washer of FIG. 23 applied to a, bolt;

FIG. 25 is a side view in section showing a nut, with a modified form of locking washer applied thereto;

FIG. 26 is. a plan view or a further modified form of washer;

FIG. 27 is a plan view of a still further modified, form of washer;

FIG. 28. is a side view in section showing. the. washer Qlf FIG. 27- applied to a nut andbolt assembly;

FIG. 29 is aside view, in section, showing a form of cutteradapted to. stamp the washer of FIG. 14 from a strip of washer stock material; 1

FIG-.. 30 is a bottom view of the cutter of. FIG. 29;

FIG. 31 is a perspective. view showing a hand tool re: cei-ving awasher which is tobev attached to a bolt. or the like; a v

FIG. 32 is a view similar to..FIG. 7, and showing. a washer substantially of the type, shown inFIG. 13 asso ciated. with a nut and bolt before tightening. Referring more in detail tothe accompanying. drawings and more particularly, at this. time, to FIGS. 1 and on r m qt ea n as e n T i form f lock washerincludes an annular body portion 10' inwardly directed prongs or tongues 12 are circumferentially spaced from one another and the inner ends of the tongues are also diametrically spaced from one another to provide a central opening. The bases or roots of the prongs are disposed along a circular line defining the washer opening, which is dimensioned so as to be slightly greater than the diameter of an externally threaded memher with which the washer is to be used.

The form of washer shown in FIG. 3 lends itself to manufacture by extrusion methods. Thus, as shown in FIG. 1, a length of stock material 14 may be extruded in conventional manner with the tongue design configuration formed internally of the stock material. As indicated by the dotted lines a, a washers of different thicknesses may be cut from the stock material 14.

The washer material is selected to be softer than the material of the threads of the threaded members with which the washer is to be used; A great many materials are suitable for this purpose, such as paper, fiber, leather, various plastics materials, such as nylon, vinyl, and the material sold under the trademark, Teflon. The plastic materials, depending upon the internal design configuration of the tongues, may be conventionally extruded into the bar or tube. stock form of FIG. 1. However, as shown in FIG. 2, the washers may also be die cut from. a strip of the washer stock material and such manufacturing procedure would perhaps be more feasible with washers of the type shown in FIGS. 14 through 17. Al though light and relatively soft metals might be employed in certain installations, the mentioned plastic or paper materials are usually preferred because of their compressibility between the mating threads, such compression of the washer material having exceptional advantages with respect to holding power under various conditions as will be pointed out hereinafter. In using metal, it may be desirable to laminate the metal with fiber, plastic or cardboard for the required ease of bending, compressibility and resiliency.

The material of the washer is preferably selected so that the washer tongues may be deformed from the fiat position of FIG. 3 to an axially inclined position by merely passing the externally threaded member through the washer within the annular body portion thereof. Thus, by reference to FIGS. and 6, the threaded shank 16 of an externally threaded member, such as a bolt, is positioned within the annular body of the washer and the two members are then telescoped relative to one another so that the end of the shank 16 will force the tongues 12 outwardly of the body portion 10, as shown in FIG. 5. Funther telescopic movement of the washer and shank will position the tongues 12 in an axially in clined position, as shown in FIG. 6. By assembling the washer and threaded shank in this manner, the tongues will be stressed and material selected for the washer is such that in this stressed condition of the tongues, they will have inherent resiliency and each tongue will tend bolt. Further relative tightening of the nut and bolt will result in the nut surface 19 forcing the adjacent portion of the washer tongues inwardly and downwardly and the material of the tongues will be caused to flow under compression between the thread surface 17 and 19, and further relative tightening between the nut and bolt will sever this top portion of each washer tongue, as shown at 21 in FIG. 10. These severed increments 21 of each tongue will be tightly compressed between the adjacent thread surfaceQso as to form lock devices with substantial sealing between the threads.

It will be noted, in FIG. 10, that the remaining por- I tion 12a of the tongue 12 has also moved inwardly by I the bolt head or the nut.

to bear inwardly against the threaded shank 16 of the externally threaded member.

As shown in FIGS. 7 and 8, a nut member has been threadedly associated with the shank 16 of a bolt .20. The initial positioning of the nut and bolt withthe interposed washer is shown in FIG. 7 and the final tightened position of the nut and bolt and interposed washer body 1 10 is shown in FIG. 8. v

To more particularly illustrate the relative tighening of the nut and bolt and the resulting action on the washer tongues, reference is made to FIGS. 9, l0, l1, and 12. The position of the nut 18 on initial contact with the washer tongues 12 is shown in FIG. 9. In this position, the upper surface of the internal nut thread 19 defines a clearance opening with the adjacent surface 17 of the external bolt thread. It will be noted that the washer tongue 12, by wardly with the upper portion of the tongue bearing against an adjacent-crestofan external-thread on the reason of its stressed condition, leans in- 1. t

reason of its stressed condition to bear against an adjacent crest of the bolt thread in position to be forced downwardly by the adjacent thread surface of the nut. Further relative tightening of the nut and bolt will effect severence of another increment 21a from each tongue, thus to provide additional locking and sealing devices between the threads as shown in FIG. 11.

Upon complete tightening between the nut and bolt, the parts will assume the positions shown in FIG. 12. In this position there remains a tongue portion 12b which may or may not be severed from the washer body. The washer body is merely compressed as a flat washer be tween the clamping surface of the nut 18 and the opposite adjacent sunface of the. mounting plate 23 or the like.

The successively severed increments 21, 21a, etc., provide multiple locking devices between the mating threads of the nut and bolt. The inherent resiliency of the tongues, when stressed to their axially inclined positions, results in the tongues being urged inwardly into position against the crest of an adjacent thread on the bolt. This serves to properly position automatically each tongue for engagement with the descending thread surface of the nut and tends to guard against any tongue being improperly deflected as the bolt and nut are tightened relative to one another.

The relatively soft and compressible materials from which the washers are made create a sufficiently high frictional resistance under compression when the bolt and nut are tightened so as to require a substantial amount of torque to loosen the same. Also, the material of the washer tongues, being deformed or caused to flow between the threads, serves not only to prevent accidental loosening of the parts, but also the loosening thereof as the result of vibration. A further and important advantage of the use of such compressible materials is that the nut and bolt may be engaged and substantially locked together with a space provided between either the bolt head or nut so that a freely rotatable arm or the like may be positioned between the support and either And still further, even after complete tightening of the nut and bolt and severing of all the successive increments of the prongs or tongues, the nut may be backed off to a position where the nut and bolt are still substantially locked together and a wrench is required to effect further complete loosening of the nut and bolt.

In FIG. 18, there is shown a base plate 25 having a frustoconical recess or countersink 26 above a threaded aperture 27. 'A machine screw 29 with a frusto-conical head and threaded shank is adapted to cooperate with the threaded base plate. In such an assembly, a slightly different form of washer is employed in that the washer has a frusto-conical base portion 28, rather than the flat annular portion of the washer of FIG. 2. Tongues may project radially inwardly from the frusto-conical portion 28 or they may be merely inclined along the same angle. In either case, the machine screw is associated with the look washer by the same telescopic movement described in connection with FIGS. 5 and 6.

Other forms of flat washers are shown in 13 through 17, FIG, .13 ,1. i n edge-of the-annular..washer ,body

Illa is provided with tongues similar to the tongues shown inwasher ofFIG. 3 ,but alternate tongues 30 are longer than adjacent tongues 31 to a greater or less extent, as may be desired. With such tongue formations, the severed increments from the longer tongues 30 can be disposed near the outer face of the nut. In FIG. 14, the tongues 32 which extend inwardly from the annular Washer body 1% are of substantially triangular configuration and separated from one another by radial slits 33. Except for the center opening shown in the washer of FIG. 14, the washer d of FIG. 16 is substantially the same with its triangular tongues 36. The material of the washer in FIG. 16 may be fiber, paper or the like, suitably coated or impregnated as desired. In FIG. 15, the substantially triangular tongues 32a are separated by radial slits 33a and around the inner limit of the washer body 100, there are provided a plurality of openlugs 34, at the base of each slit. The washer of FIG. 17 e finerally similar to that of FIG. 15, except that the tongues 3-7 are of larger area and only four punched openings 38 are provided around the inner limit of the washer body 10e. With the washers of FIGS. 14 to 17, there is substantial material at the base portions of the tongues so that a final binding action is available even without severing.

With any one of the washersshown in FIGS. 3 and 13 through .17, the tongues need not necessarily extend radially inwardly and in substantially the same plane as the washer body. In other words, the tongues might be inclined to some extent, provided they do traverse to some extent the cross-section of the bolt to be associated therewith, so that when the washer andbolt or screw are telescopically associated with one another the tongues will be. forced outwardly to a substantially annular position in which they are inherently stressed so that they tend to be urged inwardly into contact with adjacent threads of the bolt or screw in the manner pointed out above. As shown in FIGS. 5 and 6, the inner surface of the washer body 10 is only slightly greater than the external diameter of the associated bolt or the like. With such relative predimensioning, the bolt or other externally threaded member will engage the prongs or tongues adjacent the roots thereof, during assembly, and thus force the prongs or tongues to positions substantially axially extending with respect to the bolt axis although slightly inclined inwardly tolean against the boltthreads. Where the prongs or tongues are formed, as for instance in FIG. 14, with substantially increased material around the inner edge of the washer body, it may be desirable to employ an externally threaded member of somewhat lesser diameter in order to facilitate assembly of the washer with the threaded member. Such relatively predimensioned members are shown in FIG. 32 wherein the prongs or tongues 32 are inclined at a greater angle than shown in FIGS. 5 and 6, and the washer body 10b may be also slightly inclined with respect to the work surface as shown.

With the arrangement suggested in FIG. 32, it may be desirable to employ the form of washer shown in FIGS. 20 and 21. In this form of the invention, the washer body 40 is provided with internally directed prongs 41. and there is integrally attached to a small section of the outer periphery of the washer body an annular plain washer 42 of the same material. This washer '4; is provided with a central opening slightly less than the inner periphery of the washer body along the roots of the prongs. As shown in FIG. 21, the annular washer 42, is bent along itshinge line 43 to underlie the washer body 40 and serve to back up the prongs or tongues so as to prevent them from being forced axially during relative tightening between the two threaded members.

In the form of the invention shown in FIG. 19, the Washer45 with its prongs 46 is shown associated with a screw. element 47 and in this form of the invention is. provided a separate washer 48 having a central opening less than the inner periphery of the washer body 45 so as to also-back up the prongs and prevent their being forced axially of the screw.

In FIGS. 23 and 24, there is shown a modified form of washer having an annular washer body 56 and a single relatively enlarged prong or tongue 51 projecting inwardly of the central opening. This washer is assembled with the bolt 5-2 in similar manner, but the bolt is illustrated as including an axially extending flat surface 53 against which the prong or tongue 51 is resiliently urged upon assembly with the bolt. A nut 54 is threadedly engaged with the bolt and may be provided with a slight inner annular chamfer 55 which alfords a recess into which the end of the tongue 51 extends. Thus, upon relative tightening between the nut and bolt, the tongue 51 will continue to be wedged tightly against the flat surface 53' of the bolt and the exposed end of the tongue will be progressively chewed off and engaged between the mating threads as the nut and bolt are tightened relative to one another.

In FIG. 22 the bolt 56 has two opposed longitudinal slots 57. A molded plastic washer 58 carries two projecting wedge-like inserts 59. which key into the slots 57. A nut member 60 threadedly engaging the bolt threads will progressively chew 01f increments of increased thickness from the wedge-likeinserts 59 as the nut and bolt are tightened relative to one another. Thus, there is afforded an axialrange for engagement of the nut with the plastic in serts which are progressively wider toward the carrying washer member 58.

In FIG. 25 there is shown a modified form of plastic insert to be associated with a nut member 62. This insert 63 is in the form of a tubular member having one end flared as at 64. The opposite end of the sleeve 63 is shown as closed but it may be a plain open ended sleeve. A bolt or other threaded member to be associated with such a nut 62 is inserted into flared end 64 of the plastic insert and relative tightening with respect to the nut will cause the mating threads between the nut and bolt to sever successive increments of the sleeve portion 63 which increments will be compressed between the mating to provide the locking effect.

In FIGS. 26 and 27 there are shown two additional forms of molded annular washers. In the form of FIG. 26, there is an annular body portion 66 terminating at the inner edge thereof in an annular conical portion 67. In FIG. 27, this conical portion may be slit to provide separate conical tongues 68. This form of washer is shown applied to a nut and bolt assembly in FIG. 28. The nut 69 is threadedly engaged with the bolt 70 and is provided with a bottom chamfered portion 71 generally corresponding with the taper of the conical portion or the conical tongues of this type of washer so that as the nut is tightened relative to the bolt, the conical portion of the washer will be received in the chamfered portion 71 of the nut and wedged thereby into the bolt teeth so that successive sections thereof will be severed as the threaded members are tightened relative to one another. In this form of molded washer, the conical portion or portions may also be formed so as to embrace with some degree of resiliency the teeth of the bolt as the washer is assembled therewith.

An illustrative form of cutter is shown in FIGS. 29 and 30 for cutting, for instance, plural rows of washers of the type shown in FIG. 14 from a strip of stock material, as suggested in FIG. 2. The cutter comprises a head member 73 having at the bottom edge thereof annular cutting blade 74 for cutting the outside diameter of the washer from the stock material. Within the head member 73 there are provided radially extending slitting blades 75 corresponding in number to the type of washer being. formed, Centrally disposed within the slitting blade 75 is a punch member 76 to form the central hole in the washer by passing through a'complemental aperture 77 in the bed plate 78 which serves as the anvil'for the slitting knives and the annular cutter 74. Thus, the above described cutter acts against the bed plate 78 in the nature of a cookie cutter in forming the washers and severing the same from the stock material. To facilitate stripping of the formed washers from the cutter head, the interior space 79 within the annular cutter 74 may be packed with rubber which is compressed against the stock material during the cutting operation and which, upon removal of the cutter head 73, will expand slightly to assure removal of the cut washer from the cutter edges. Thus, the rubber packing 80 serves as an ejector so that the cut washers will not stick to the edges of the cutters carried by the cutter head 73.

InFIG. 31 there is shown a hand receptacle or tool to facilitate application of a washer to a bolt. This hand tool comprises a body member 81 having a central bore or recess 82 of a size permitting insertion of the threaded shank of a bolt. The outer end of the tool is tapered inwardly, as at 83, to the recess and the outer edge of the tapered portion is circumferentially recessed, as at 84. A Washer, such as of the type shown in FIG. 14, is placed in the tapered portion of the tool with the outer edge of the Washer body engaged in the circumferential recess. Thus, the washer is somewhat dished as it is inserted in the tool and thereafter a bolt can be conveniently passed through the washer to incline the prongs and the degree to which the bolt is. inserted will determine the positioning of the washer along the bolt axis.

With a compressible and inherently resilient material, the washers are such that the increments severed therefrom will be compressed tightly with resilient binding action between mating threads on the fastener members. Of the various forms of washers with tongues, the association of such washers with the bolt or the like is such that there is merely a bend between the bottom portions of the tongues and the annular washer body so that the tongues are stressed against their inherent resiliency. In this manner, the tongues tend to lean toward or into bearing engagement with adjacent threads on the bolt or the like. In other words, there is no pre-set given to the tongues but the tongues tend to constantly be urged inwardly toward the bolt threads. As the fastener members approach the completely tightened position, the remaining portions of the tongues may not be completely severed but may, in a sense, have a thread cut therein by the fastener members acting as die members. This is illustrated by the remaining portion 12b in FIG. 12. Such action may be more pronounced with the form of washers shown in FIGS. 14 through 17 wherein a substantial amount of material. remains at the base portions of the severed tongues. Likewise, with the tapered plastic inserts 59 of FIG. 22 and the conical inner portion of the washers shown in FIGS. 26 and 27, the initial action by the nut may be to sever the upper thinner edges but further tightening may simply result in a die impressing action. Thus, there is the combined action of perhaps severing some material and impressing a thread formation on the thicker part of the washer which results in this portion of the washer being compressed to give a resilient binding action between the threads. Thus, in essence, each form of washer includes an annular base portion with axially projecting portion providing a thread locking portion, whether severed or remaining deformed and compressed between the threads for the resilient binding action. With the forms of washers shown in FIGS. 22, 26, and 27, the inserts or the conical portions may be formed to also tend to hug the threads of the bolt or the like, as previously mentioned in connection with the tongued washers. With washers tending to hugthe ex ternally threaded member when assembled therewith, there is sufiicient friction to hold-the-same in assembled position and to also locate the washer in any predetermined position on the shank of'the externally threaded this invention is that the washers are formed of a material.

which will not damage or alter the thread surfaces of the internally and externally threaded members which,

may, therefore, be re-used.

While certain forms of the invention have been shown for perhaps the illustration, it is to be clearly understood that various changes in the details of construction and arrangement of parts may be made without departing from the scope and spirit of the invention as set forth in the appended claims.

We claim: 1 v

1. In a fastening device in which an externally threaded member is adapted to be threadedly engaged with a complementary internally threaded member with a lock washer positioned therebetween which lock member comprises an annular base portion in surrounding relationship with respect to the externally threaded member and through the aperture of which the externally threaded member is adapted to extend, said annular base portion having a thread locking tongue formed integral with the base portion and being inherently resilient and initially extending inwardly from the base portion and bent upwardly under stress adjacent its juncture with the base portion to an angular position approaching a predominantly substantially axial position from the base portion upon relative insertion of the externally threaded member through the aperture within the annular base portion, the free extremity of said tongue bearing inwardly against a thread of the externally threaded member as the result of the outwardly stressed condition thereof and being of relatively thin cross-section and of sufiiciently narrow width to fit into the space provided by a thread on the externally threaded member and the adjacent surface of the complementary internally threaded member, said tongue being of a length at least twice the pitch distance of the threads on the internally threaded member and of a material relatively softer than that of the threads on said threaded members and forced between adjacent threads of said threaded members with successive increments thereof being severed upon relative rotation of said threaded members and compressed between converging threads thereon and with the remaining free end portion of said tongue under the continuing stressed condition thereof resiliently bearing against another adjacent thread of the externally threaded member and fitting into the space between such thread and the adjacent surface of the complementary externally threaded member after each increment is severed upon relative tightening of said threaded members.

2. In a fastening device as claimed in claim 1, wherein the lock washer and tongue areformed of a plastic material having inherent resiliency and compressibility.

3. In a fastening device as claimed in claim 1, wherein the locking tongue comprises a base portion wider than the free extremity thereof to present increasing amounts of material to be compressed between the mating threads as the threaded members are tightened relative to one another.

4. In a fastening device in which an externally threaded member is adapted to be threadedly engaged with a complementary internally threaded member with a lock washer positioned therebetween which lock member comprises an annular base portion in surrounding relationship with respect to the externally threaded member and through the aperture of which the externally threaded member is adapted to extend, said annular base portion having a plurality of thread locking tongues formed integral with the base portion and being inherently resilient'and initially extending inwardly from the base portion and bent upwardly under stress adjacent its juncture with the base portion to. an angular position approaching a'predominantly substantially axial position from the base portion upon relative insertion of the externally threaded member through the aperture within the annular base portion, the free extremities of said tongues bearing inwardly against a thread of the externally threaded member as the result of the outwardly stressed condition thereof and being of relatively thin cross-section and of sufliciently narrow width to fit into the space provided by a thread on the externally threaded member and the adjacent surface of the complementary internally threaded member, said tongues being of a length at least twice the pitch distance of the threads on the internally threaded member and of a material relatively softer than that of the threads on said threaded members and torced between adjacent threads of said threaded members with successive increments thereof being severed upon relative rotation of said threaded members and compressed between converging threads thereon and with the remaining free end portion of said tongues under the continuing stressed condition thereof resiliently bearing against another adjacent thread of the externally threaded member and fitting into the space between such thread and the adjacent surface of the complementary externally threaded member after each increment is severed upon relative tightening of said threaded members.

5. In a fastening device as claimed in claim 4, wherein the plural locking tongues are separated by radial slits.

6. In a fastening device as claimed in claim 4, wherein the base portions of the locking tongues are circumferentially spaced from one another around the inner edge of the annular base portion.

7. In a fastening device as claimed in claim 6, wherein alternate locking tongues extend inwardly a greater distance than intermediate tongues.

8. In a fastening device as claimed in claim 4, wherein there is provided an additional washer member integral with said annular base portion and wherein the inner edge of said additional washer member projects inwardly of the inner periphery of said annular base portion to provide a backing for the locking tongues during relative tightening of the threaded members.

References Cited in the file of this patent UNITED STATES PATENTS 2,197,220 Kost Apr. 16, 1940 2,250,343 Zigler July 22, 1941 2,492,115 Crowther Dec. 20, 1949 2,561,679 Waller July 24, 1951 2,639,832 Bergstrorn May 26, 1953 FOREIGN PATENTS 1,105,172 France June 2.9, 1955 

